Bluetooth: H4: added support for HCI vendor-specific Setup feature.

Updated H4 driver to initialize setup function. Finally bt_h4_vnd_setup
function must be implemented in vendor-specific HCI extension module if
CONFIG_BT_HCI_SETUP is enabled.

BT_HCI_SETUP feature is useful when the BT Controller requires execution
of the vendor-specific commands sequence to initialize the BT Controller
before the BT Host executes a Reset sequence.
To enable this feature the CONFIG_BT_HCI_SETUP should be enable.

Fixes #41140

Signed-off-by: Nazar Palamar <nazar.palamar@infineon.com>